A)Lake trout are bigger so their bodies can store a greater quantity of PCBs.
B)PCBs dissolve poorly in water but readily in fat; lake trout have a higher percentage of body fat than minnows.
C)Lake trout are large and long-lived; when they respire they pass water over their gills allowing the PCBs in the lake to accumulate in their bodies.
D)Lake trout fed on minnows, whereas minnows fed on crustaceans.

A)removes carbon dioxide from the atmosphere.
B)is causing a hole in the ozone layer.
C)has greatly increased the extent of human participation in the nitrogen cycle.
D)reduces the amount of acid rain.

A)an increase in average global temperature.
B)cooler average temperatures as carbon dioxide reflects sunlight back into space.
C)an acceleration of the depletion of ozone.
D)an increase in the pH of oceans and lakes.